Process for plating stainless steel and articles produced therrby



A. HARPER PROCESS FOR PLATING STAINLESS STEEL AND ARTICLES PRODUCED THERBBY Original Filed Dec. 24, 1921 made Patented m 15, 1924.

. UNIT D" STATES PATENT OFFICE.

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' Application filed December 24, 1921, Serial No. 524,700. Renewed July 17, 1928.

To all whom it may concern:

Be it known that I, ALEXANDER Hansen, a citizen of the United States of America, residing at Bristol, Connecticut, have 1nventeda new and useful Process for Plating Stainless Steeland Articles Produced Thereby, of which the following is a specification.

My invention relates to a new and improved rocess for surface finishing articles f so-called stainless steel and articles produced thereb Such articles are described and claime in the Brearley Patent #1,197,256 dated September 5th, 1%?16. For-the urpose of the present. applicatlon, I shall escribe my process as apphed to the finishing of a handle of a steel table knife.

In the accom anying drawing: Fig. 1 is a si e elevation of a table knife, conventionally illustrating the appearance of the handle portion after the article has been subjected to the first step in my proc- Fig. 2 is a similar view of the same article in a finished state, that is to say, after it has been subjected to the final step of the process. I

1 represents the polished blade portion of a table knife. 2 represents the handle portion thereof which is formed integrally with the blade. The article is made throughout from so-called stainless steel which comprises substantially a ferrous alloy containing between nine per cent (9%) and sixteen per cent' (16%) of chromium tenths and carbon in quantity less than seven per cent (.7 and preferably not containing any microscopical y d1st1n ulshable free carbids. Otherwise stated, t e article is made from a metal-alloy such as set forth and claimed in the aforesaid Brearley patent, which article, as is well known,

possesses to a remarkable degree the quality of being ractically untarnishable, and which artic es have so far satisfied that claim that the steel em loyed in such art1- cles has become widely own as'.sta1nless steel.

Heretofore, it has been regarded as ractically impossible to successfully app y to the hardened and olished surfaces 0 art1- cles made from suc steel, a, durable electro: plated surface finish.. I have found that by subjecting the surface of such articles to the appearance of the hand kmfe after it has been su jected to the ac- .cess

cles are usually ut.

'ver even thoughv such handle portion is made of an untarnishable steel. 1ngly, in carrying out my process Accord- I first thoroughl clean the articles and then im-' merse suc portion or portionsas it is desired to electro-plate in a solution which contains substantially one part of h drofluoric acid, six parts nitric acid and t irtytwo anduntarnishable surface in such a manner as to render it relatively rough and make it peculiarly receptive to an electro-plated de osit of silver.-

n Fig. 1, I have indicated conventionally and relatively exaggerated, the rouglh e ortion of a tab e tion of the aforesaid acid solution. After the article has been thus treated, the surface which has been thus re ared is immersed in an electro-plating at and subjected to the usual plating treatment, the handle, after such treatment, being represented in Fig. 3. I havefound that by this. process an entirely satisfactory and commercially successful article can be produced.

While I have described herein the .proportions of an acid solution which, I know parts water. I have'found that such a solution will attack the otherwise smooth so I from actual ex erience will successfully prepare the sur ace of a stainless steel article for electro-plating, it should: be understood that this solutlon may be somewhat changed the im rtant thing being to provide a solution t at will successfully prepare the surface which it is desired to plate byfrendering it relatively rou h so that the metal deposited thereon will so cling thereto with such tenacity as to suelly resist the uses to which such arti- What I claim 1s:

1. The recess of finishing the hardened and smoot surface of an article composed of a ferrous alloy containing between nine per cent (9%) and sixteen per cent (16%) .of chromlum and carbon in quantity less than seven tenths per cent (.7 comprising subjecting the surface of such an article to the action of an acid that Wlll. render such surface relatively rough and then depositand smoot ing a difierent metal upon such relatively rough surface by an electro-plating process.

2. The rocess of finishing the hardened surface of a cutle article'composed of a ferrous alloy contaming between nine er cent (9%) and sixteen per cent (16%) of chromium and carbon in quantity less than seven tenths per cent (.7%) comprisingsubjecting thesurface of such an ar-- tween nine per cent (9%) and sixteen per cent (16%) of chromium and carn in quantity less than seven tenths I percent (.7 which comprises subjectmg such a ortion of the surface as itis desired to ish to the action of an acid solution containing substantially one part hydrofluoric acid, six parts nitric acid and thirty-two parts water until such surface is relatively roughened by the action of such .acid and thereafter. depositing different metal upon such relatively rough surface by an electro-plating process.

4'. The rocess of finishing the hardened surface of anarticle of steel which comrises subjecting such portion of the surace' as it is desired to finish to the action of a solution containing. substantially one part hydrofluoric acid, sixparts nitric acid and thirty-two partswater until such surface is relatively roughened by the action of such solution, and thereafter depositing a I different metal upon such relatively rough surface by an electro-plating process.

5. The process of finishing the surface of an article formed of carbon steel containing chromium and which has been treated to .render same relatively non-corrodible by weak acids, comprising subjecting such portion ofthe surface as it is desired to finish to theaction of an-acid solution containing hydrofluoric'acid until such surface is relatively roughened, and then depositing a dif- Y 'bein ar y mea est ferent metal upon such relatively roughened surface by an electro-plating process.

6. The'process of finishing-the surface of an article formed of steel containing carbon and chromium and which has been treated to render the same relatively noncorrodible by weak acids, comprisin subjecting such portion of the surface 0 such article as it is desired to finish to the action of an acid that will render such surface relatively rough, and then depositin a different metal upon such relatively roug surface by an electro-plating process.

7. The process of finishing the surface of an article formed of carbon steel containing between nine per cent (9%) and sixteen per cent (16%) of chromium, comprising subjecting such portion of the surface of such article as it is desired to finish to the action of an acid that will render such surface relatively rough, and then depositing a different metal upon such relatively rough surface by an electro-plating process.

8. As an article of manufacture, an article formed of steel containing carbon and chromium and which is relatively non-corrodible by weak acids, at least a portion of said article being coated with a different metal integrally joined thereto.

9. As an article of manufacture, an article formed of carbon steel containing between nine per cent (9%) and sixteen percent (16%) of chromium, at least a portion of said article being coated with a different metal integrally joined thereto.

10. As an article of manufacture, an article of tableware composed of a ferrous alloy containing between nine per cent (9%) and sixteen per .cent (16%) of chromium,v

and carbon in uantity less than seven-tenths per cent (.7 a portion of said article being coated with ,a different metal integrally 'oined thereto.

' 11. s an article of manufacture, a. knife having integral handle and blade portions formed of a ferrous alloy containing between nine per cent (9%) and-sixteen per cent (16%) of chromium, and carbon in quantity less than seven-tenths per cent (.7 the handle portion of said knife coated with a different metal intejoined thereto.

ALEXANDER HARPER. 

